Each bath of honey delivered at Meli is screened against several parameters.
These analyses can be carried out both in the in-house lab and externally.
Only after release by the lab can the batches in question be processed.
Determination of the fructose, glucose and sucrose content in honey. These sugars are present in nectar, but in different proportions (more fructose and glucose; less sucrose).
The bee treats the honey by adding enzymes so that the sugar composition changes. For fructose + glucose there is a legal minimum of 60%, while there is a legal maximum of 5% for sucrose.
An exception is made for orange blossom and acacia honey (10%).
The sugars are determined chromatographically. The sugars are separated by an HPLC and detected by a differential refractometer.Standards are used to draw up a standard measure which can then be used to determine the fructose, glucose and sucrose content of the sample.
The F/G proportion is used to add the designation of the honey: liquid or solid honey.
Moisture content may not be too high as yeasts may otherwise start developing in the honey.
Legally, honey may contain 20% moisture maximally.
Measurements are carried out by means of a refractometer.
Determination of the 2-hydroxymethyl-5-furfuraldehyde (hydroxymethylfurfural or HMF) content in honey. HMF is hardly or not at all present in honey only just harvested.
It is always formed afterwards from the sugars in honey under the influence of an acid environment (always present in honey; pH = ± 4) and heat. This reaction is irreversible and thus constitutes a criterion for the manner in which honey is treated. At room temperature the increase in HMF is limited; at high temperatures the HMF increases quickly.
The HMF content also increases due to the age of the honey.
HMF is determined spectrophotometrically. The UV absorbance of a cleared solution of honey in water is measured by means of a reference solution in which the HMF is reduced by bisulphite.
Legally the HMF content may not exceed 40 mg/kg. A higher content is allowed for honey processed into other products (baker’s honey) and honey of tropical origin.
Determination of the diastase (or 2-amylase) activity in honey.
Diastase is an enzyme catalysing the breakdown of starch that occurs in human and animal saliva. It is added to the honey by the bees. Diastase is broken down when honey is heated and is therefore a criterion for the manner in which honey is treated.
There is a legal minimum value of 8 Schade units.An exception is made for acacia and orange blossom honey: 3 Schade units.
Diastase is determined spectrophotometrically. The diastase number (expressed in Schade units) indicates how many grams of starch can be hydrolysed in 1 hour by the enzyme present in 1 gram of honey. An insoluble and blue-coloured starch polymer is used as a substrate.
The substrate is hydrolised by the diastase present in the honey and this produces blue, water-soluble parts determined spectrophotometrically at 620 nm. The absorbance of the solution is directly proportional to the diastase activity of the sample.
The colour of the different kinds of honey is not legally determined. Some honey is nevertheless bought with certain colour specifications (white, extra light amber, light amber). The colour of the honey is important to obtain a constant end product for the consumer.
The colour is determined with a Pfund Colour Grader. The colour of the honey is compared with the colour of a prism; at the moment on which both colours are identical, the colour of the honey can be read directly.
Pfund Color Grader:
- 0-8 mm: water white
- 8-16,5 mm: extra white
- 16,5-34 mm: white
- 30-45 mm: extra light amber
- 50-85 mm: light amber
- 85-114 mm: amber
- > 114 mm: dark amber
These pesticides may originate from the nectar or from products used to fight bee diseases.
The pesticides are determined chromatographically.
The sugars are separated by a GC and detected by a mass spectrometer (MS). The spectra can be identified by means of a spectra library. In case of a positive analysis the content can be determined by means of an internal standard.
Clostridium botulinum is a Gram-positive anaerobic spore-forming bacterium growing in the absence of oxygen. Clostridium botulinum is responsible for 4 epidemiologically different illnesses: foodborne, infant and wound botulism and another form which has not yet been given a specific classification.
In case of foodborne botulism the contamination results from eating toxins produced in food products. In the case of infant botulism not the toxins but the spores of the bacterium end up in the bowels. As the intestinal flora of children up to 1 year old has not yet developed completely, the spores may germinate, as a result of which toxins may be produced in the bowels. This can have very serious consequences.
In some countries (e.g. England) the label mentions that honey is not suited for children under 1 year of age.This is not yet the case in Belgium.Since 24/01/01, Meli has been checking all raw materials for the presence of sulphite-reducing anaerobics in an external lab. Clostridium Botulinum may occur in honey and can possibly cause infant botulism.
Clostridium botulinum belongs to these anaerobic bacteria. The standard is set to less than 1/g. If the test on sulphite-reducing anaerobics is higher than this 1/g, an additional analysis will be carried out on Clostridium botulinum itself. For this bacterium the standard is less than 1/g as well.
Antibiotics may be present in honey as a result of treating ill bees.If the waiting period is respected, the honey of the bees is free from antibiotics.
The Belgian antibiotics standards have been changed regularly in the course of the years.
- 1/1/2002 200ppb Streptomycins 50ppb Sulphonamides 50ppb Tetracyclines
- 1/7/2002 100ppb Streptomycins 20ppb Sulphonamides 20ppb Tetracyclines
- 1/1/2003 50ppb Streptomycins 20ppb Sulphonamides 20ppb Tetracyclines
- 1/7/2003 20ppb Streptomycins 20ppb Sulphonamides 20ppb Tetracyclines
At Meli honey is currently screened against the following antibiotics:
In the case of streptomycins, sulphonamides and macrolides the analysis takes place on the basis of the charm II system. This is a radio-immune assay (RIA). If the result is positive, an additional analysis will take place with the assistance of LCMS. We follow the developments closely so as to be able to carry out additional analyses.
Sometimes tea discolours when honey is added. The tea turns black.
This is due to the iron content of honey. This is tested by adding honey to tea and looking at the possible discoloration.